A thermal printer prints on a paper including a heat-sensitive layer by heat generated by each of a plurality of heat generating elements which constitutes a thermal head. The printing density by the thermal printer is changed depending on a strobe signal applied to each of the plurality of the heat generating elements which constitutes the thermal head.
On the other hand, such a thermal printer supports various types of papers. Different types of papers include substances which are different from each other. Thus, characteristics of the papers are different. Furthermore, even if the types of the papers are the same, the characteristics of the papers can be different corresponding to different storage conditions (such as differences in temperature, humidity, storage period, and the like) of the papers.